I thought that higher powered eyepieces (RE:short Focal Length eyepieces) produced less image intensity due to the smaller field stop and area of lenses????
Subsequently, wide field low power EPs should have a brighter image compared with 45degree Plossls, with regard to field stop size and area of lenses??
But there again the image plane is (usually) bigger with wide field EPs so...maybe the intensity of light is spread over this plane..a greater area.
Higher power also produces a larger image (lets say with Jupiter) and the target image intensity is thus spread over a larger area, thus it appears less bright?
Anyone else?
edit;
yep image intensity at focal plane (for large objects) declines as the square of magnification. This shouldn't effect star viewing though as they are point sources.
reference:
http://www.mira.org/ascc/pages/lectures/eyepiece.htm